On the bottom of my page there are some boxes related to search things. I tried everything but they do not go away.
How can I delete them?
You can click the ‘X’ at the top right to close the search portals. They are always present in collapsed form at the bottom of each rem in the editor, so you cannot really delete them.
I did like you said and clicked X. But these still remain.
As mentioned above, they are the search portals that will be there at the bottom of each rem. You can collapse them or expand them to use. But I don’t think you can get rid of them.
You can hide them if you want using CSS, or just set a transparency so they aren’t so intrusive.
This seems to work (delete the display one if you want opacity):
#ReferenceLinks {
opacity: 20%;
display: none;
}